1. Field of the Invention
This invention relates to systems and methods for identifying, locating, and managing inventory of sterilized medical devices located within a sterilization case that is sealed with a wrap in preparation for a surgical procedure.
2. Related Art
Surgical procedures generally involve various sterilized instruments. Sterilization can occur by known techniques such as autoclaving or those utilizing substances such as ethylene oxide, vapor hydrogen peroxide, or ozone. Before sterilization, the surgical instruments are placed inside a sterilization case that is typically made from steel, aluminum, titanium, or plastic. A sterilization case also may be referred to as an instrument tray or instrument case. The sterilization case is then wrapped in a plastic sheet and sealed. The plastic normally allows particles, condensed water, water vapor, and other substances to leave the sterilization case but prevents foreign contaminants from entering the sterilization case. Upon completing the sterilization process, the sterilization case containing the medical instruments is still within the sealed wrap. Prior to the surgical procedure and in the sterile field of the operating room, the instruments are typically removed from the wrap and sterilization case, placed on a table, and counted to validate that all instruments needed for the particular surgical procedure are on the table.
The tracking and management of surgical instruments in hospitals, instrument management companies, and sterilization companies is important to the efficiency and safety of use of hand held medical or surgical instruments. Inventory tracking is difficult to manage given that the instruments pass through the purview of various parties in the supply chain. Most hospitals in the United States have from 3,000 to 5,000 different types of instruments which are organized into 300 to 600 different types of sets. The content of these sets changes frequently. Moreover, individual devices within these sets become damaged and then require repair or replacement. It is desirable to be able to identify an inventory of the medical instruments to facilitate repair and replacement of these instruments should they become broken or worn. Instruments also can be misplaced, which may remain unknown until the instruments are removed from the sterilization case and the wrap in the sterile field of the operating room prior to surgery. If one or more instruments needed for the surgery are missing, hospital personnel must open another sealed plastic wrap to retrieve the missing instruments or locate a replacement within the hospital. Considerable time is required searching the hospital for a replacement to obtain a complete set of necessary instruments, which often involves opening other sealed cases. In the meantime, a patient is under anesthetic in the operating theatre waiting to be treated at a cost of $100 per minute and can often be delayed by fifteen minutes whilst hospital staff search for missing instruments. Once the instruments are retrieved, the remaining instruments in the opened cases have to be re-sterilized. Many healthcare facilities do not have effective solutions in place for tracking and management of surgical instruments, which is likely to grow as more instruments are purchased from manufactures. However, there is an increasing trend towards healthcare companies providing additional value to hospitals by tracking the hospital's entire inventory and ensuring that instruments are in fact in the instrument tray.
Hospitals, instrument management companies, and sterilization companies often have difficulty tracking and managing surgical instruments as they pass through the purview of various parties in the supply chain. For instance, instruments are sometimes misplaced, which may remain unknown until the instruments are removed from the sterilization case and the wrap in the sterile field of the operating room prior to surgery. If one or more instruments needed for the surgery are missing, personnel must open another sealed plastic wrap to retrieve the missing instruments or locate a replacement within the hospital. Personnel associated with surgical preparation sometimes need to open several sealed cases before they obtain a complete set of necessary instruments or spend time searching the hospital or other facility for a replacement. Furthermore, the remaining instruments in the second sterilization case and those opened thereafter, even if not used in a surgical procedure, always must be sterilized again.
Tracking individual instruments to specific trays is very challenging because each individual instrument needs to be scanned to the tray to form a link between the instrument and the tray, which is a labor intensive process. The techniques used to track surgical instruments include manual counting, color-coding and memory devices, which are discussed in turn below.
Various methods of counting the surgical instruments are known but none are particularly efficient. Manual counting involves a skilled technician physically counting each instrument on the surgical instrument tray and then comparing the count result to an information sheet that provides an inventory list of instruments used in a particular surgery. This count is usually performed close to, but before, the scheduled surgery while the patient is either already on the surgical table or on their way to the surgical room. If there is a discrepancy between the count and inventory list, the person counting or their assistant must quickly determine which instrument is missing and where a suitable replacement may be located before the surgical procedure begins. This tracking technique is unreliable and labor intensive because significant time is required to count the instruments manually, determine if there is a discrepancy between the count and the inventory list, and locate a replacement instrument before the surgical procedure begins. This time is costly to both the instrument company and hospital and could needlessly delay surgery. In addition, there is a likelihood for human error in counting the instruments and comparing the count to the inventory list. Furthermore, the correct instruments for a particular surgical procedure may still be missing during surgery, forcing the surgeon to use a closely related, but incorrect, instrument to perform the procedure. Manually tracking medical instruments also requires that the surgical instruments be removed from the wrap and the sterilization case before they are counted and compared to the inventory list for discrepancies.
A less common approach to instrument tracking includes color-coding techniques to identify different surgical instruments. Others optically mark each instrument and later scan the instruments with a hand-held scanner that is connected to a data terminal to ascertain the history of that instrument. Such a method typically requires that the instrument be removed from the tray on arrival and scanned by humans, a method that is costly and time-consuming. In addition, colors can fade and a significant percentage of the population is color blind.
Other methods to count surgical instruments and compare to an inventory list involve electronic mechanisms. Data carriers such as memory devices are a more expensive alternative method for manually counting surgical instruments and comparing them to an inventory. Memory devices permit the linking of large amounts of data with an object or item. Memory devices typically include a memory and logic in the form of an integrated circuit and a mechanism for transmitting data to and/or from the device.
One such method utilizes an optical scanner, in communication with a computer and database, which reads an encoded optical pattern of a bar code attached to each surgical instrument. Individual surgical instruments may be identified by the encoded optical pattern of the attached bar code. The optical scanner usually converts the encoded optical pattern of a bar code into an electrical signal that represents an identification code associated in the database with a particular surgical instrument. The computer typically contains a memory with database information about each surgical instrument and correlates that information to the identification code. The computer may then be programmed to produce information to a user in a variety of formats useful in an inventory procedure.
An optical tag is one form of memory device, which relies on an optical signal to transmit data to and/or from the tag. The optical scanner converts the encoded optical pattern of a bar code into an electrical signal that represents an identification code associated in the database with a particular surgical instrument. Thus, individual surgical instruments may be identified by the encoded optical pattern of the attached bar code. There are a number of disadvantages to the use of optical tags. First, the size of a bar code is too large for placement on relatively small surgical instruments. Second, the time required to scan and inventory a group of medical instruments can be quite lengthy, which can needlessly delay a surgical procedure. Third, optical scanning techniques require the user to present the optical scanner in close proximity to and in the line of sight of the bar code on each surgical instrument and orient the scanning device appropriately to the bar code. Furthermore, each surgical instrument and attached bar code must be scanned individually. Finally, the optical scanning procedure is prone to human error. If the user does not orient the optical scanner correctly with respect to a bar code on a surgical instrument, the scanner could fail to read that item and it could be deemed missing when it is actually present in the surgical instrument group.
Another method for managing medical instrument locations prior to and during surgery utilizing electronic mechanisms involves attaching certain radio frequency identification (RFID) tags to surgical instruments and a reader that obtains information associated with the particular medical instrument through radio frequency. A second type of memory device is the radio frequency identification (RFID) tag, which typically includes a memory for storing data, an antenna, an RF transmitter and receiver or an RF transceiver to transmit data, and logic for controlling the various components of the memory device. RFID tags can either be passive or active devices. Active devices are self-powered, by a battery for example. Passive devices do not contain a discrete power source but derive their energy from an RF signal used to interrogate the RFID tag. A reader is used to obtain information associated with the particular medical instrument through radio frequency. The reader is in electrical communication with a computer system having a database of information about the inventory. After detecting the radio frequency signal from the RFID tag, the reader causes the computer system to change the data in the database to account for the presence of a particular inventory item. If each instrument was embedded with an RFID tag and the tray in which the instruments are placed is retrofitted with a RFID reader, instruments could be identified and logged the moment they are placed in the tray. RFID tags typically comprise an electronic circuit placed on small substrate materials. The electronic circuits contain encoded data and transmit or respond (actively or passively) with encoded or identifiable data as a radio frequency signal or a signature when an interrogation radio frequency signal causes the electronic circuit to transmit or respond (whether actively or passively). Some RFID tags are able to have their data modified by an encoded radio signal.
A reader is a radio frequency emitter/receiver or interrogator. In accordance with general RFID tag methodology, the reader interrogates RFID tags that are within its range by emitting radio frequency waves at a certain frequency. Each tag may respond to a unique set of interrogation frequencies. An RFID tag typically responds to an interrogation by emitting or responding with coded or identification information as a radio frequency signal or signature and this signal or signature (whether actively or passively) is detected by the reader. The reader is in electrical communication with a computer system having a database of information about the inventory. After detecting the radio frequency signal from the RFID tag, the reader causes the computer system to change the data in the database to account for the presence of a particular inventory item.
An RFID tag system has several advantages over manual counting and optical scanning systems. For instance, the RFID tag reader is not required to be aimed directly at a tag in order to detect a signal. An RFID tag system does not require the user to orient a reader with respect to a particular tag in order to obtain the information as the optical scanning system requires. An additional advantage of an RFID tag system is the capability of quickly performing an inventory of a large group of items by successively reading a tag associated with each item without requiring the user to perform multiple procedural steps. This saves time and expense relative to manual and optical scanning systems.
In theory, RFID tagging is an ideal solution for tagging individual instruments. However, it is also a very challenging proposition given current limitations with RFID technology. Any device attached to a medical device or surgical instrument must be capable of performing despite being attached to various metals. It is difficult to apply and read RFID tags on metallic alloys because they tend to either absorb or reflect RF signals. This is a problem because many surgical instruments and implants are metallic interfering with weak RF signals of either the reader or tag, thus reducing the system's read range. The sterilization case is also metallic preventing electromagnetic energy, such as a radio frequency signal, from entering or leaving the case. Thus, an RFID reader is unable to communicate with the RFID tags located inside the sterilization case and the instruments must be removed from the case, including breaking the sealed wrap, in order for the reader to determine the inventory of a particular group of instruments. If, after reading the removed medical instruments, the medical instrument group does not include an instrument necessary for the particular surgical procedure, hospital or medical instrument company representatives must break another sealed sterilization packet, remove the instruments from the case and read or interrogate the RFID tags of that group to find the instrument necessary to complete the first instrument group. This process includes high costs and time delays in preparing for a surgical procedure.
Tag reliability can be impacted by environmental factors such as humidity, radiation and temperature. Previously, commercial-off-the-shelf RFID tags could not withstand extreme temperatures without a temperature-resistant housing. For that reason, using them for items like surgical instruments which undergo an autoclave or dry heat sterilization cycle is complicated. Costs are presently very high for custom chips, and tags capable of surviving the temperatures in a sterilization cycle would have to pass very close to an RFID-reader.
Known RFID tag systems have been used to manage medical instrument locations prior to and during surgery. For instance, the individual instruments may be scanned prior to the surgery to ensure that all instruments needed for the procedure are present. Prior to completing the surgery, the surgical tray table may be scanned again to ensure that instruments are located on the tray table instead of inside the patient. Some RFID tag systems describe scanning the surgical cavity of the patient to check for the presence of any instruments prior to completing the surgery.
Previous and current RFID tag systems used to manage and inventory medical instruments require that surgical personnel break the sterilization seal of a group of instruments and remove the instruments from the packet before the reader reads medical instruments. This is because instruments are typically contained within a metallic sterilization case and the sterilization case prevents electromagnetic energy, such as a radio frequency signal, from entering or leaving the case. Thus, an RFID reader is unable to communicate with the RFID tags located inside the sterilization case and the instruments must be removed from the case, including breaking the sealed wrap, in order for the reader to determine the inventory of a particular group of instruments. If, after reading the removed medical instruments, the medical instrument group does not include an instrument necessary for the particular surgical procedure, hospital or medical instrument company representatives must break another sealed sterilization packet, remove the instruments from the case and read or interrogate the RFID tags of that group to find the instrument necessary to complete the first instrument group. This process includes high costs and time delays in preparing for a surgical procedure.
A medical instrument inventory and management system that allows personnel to read data regarding the individual medical instruments contained within a sealed sterilization case would decrease the time necessary to locate a particular instrument. In addition, determining the presence of particular medical instruments inside a sealed sterilization case could decrease the time and cost of preparing for a surgical procedure because breaking a second and additional sealed packets requires another cleaning, decontamination, and sterilization process. Furthermore, personnel could read the inventory of several packets and select the one with the correct instrument group for a particular medical procedure.
Further, there is a problem in locating missing instrument trays, implant trays, and devices. For example, a tray may be lost at a hospital and hospital personnel are not able to locate the tray in time for surgery. Another example would be the tray lost in delivery or sent to an incorrect facility.
Sometimes a surgeon does not know how to use an instrument correctly or know what the next step is in a complicated surgical procedure. An example may be a resident using an implant system in the middle of the night and not knowing whether to perform step A or step B in the surgical procedure.
Hospitals face significant costs in managing inventory. Currently, a sales representative must review the inventory and determine if the hospital has an adequate amount of each product. If the sales representative determines that inventory is low, then the sales representative places an order to replenish the stock.
It would be of significant benefit if the instrument trays and surgical instrument inventory could be tracked. Tracking assets, physical inventory, and other objects in a large-scale enterprise is a daunting task. Traditionally, this requires a manual, physical inventory that must be regularly repeated. Further, as assets move from place to place, or out of the control of the enterprise, the conventional process requires a time-intensive paperwork trail to track the movement of the assets.
This already-daunting task is made even more difficult when the assets being tracked are physically similar because in that case every specific serial number must be verified to conclusively identify the specific item.
Recently, for items such as shipping containers, RFID tags have been used to partially automate this process in a real-time location system (RTLS). In the common case, an asset with an attached RFID tag transmits a unique identifier, allowing an RFID tag reader to easily receive the transmitted ID number and thereby identify specific shipping containers.
An entirely different type of asset location is used for locating stolen vehicles. A commonly known system of this type is the “LoJack” system manufactured by the LoJack Corporation of Westwood, Mass., and described in U.S. Pat. Nos. 4,818,998, 4,908,629, 5,917,423, and 6,665,613, all of which are hereby incorporated by reference. In general terms, this type of system uses a remotely activated system to track a vehicle in motion, using transceivers installed in the target vehicle in combination with transceiver/detectors mounted on other vehicles. Typically, a LoJack system is used to track stolen vehicles. When a target vehicle is reported stolen, its transceiver is remotely activated, and thereafter police units that are specially equipped with transceiver/detectors can detect and locate the target vehicle.
LoJack is a form of an asset location system that utilizes a special FCC-allocated radio frequency (173.075 MHz), an older technology, very high frequency (VHF) signal. The LoJack transceiver is passive until activated by police radio towers, and specially equipped police cruisers with receivers must work together to triangulate and locate the target vehicle. LoJack does not utilize global positioning satellites (GPS) for location information.
Another type of long-range vehicle-tracking system uses GPS to identify the current location of a vehicle. In this case, a GPS receiver is mounted in the vehicle to determine the vehicle location, and a separate transmitter is used to send the location data to the person or entity tracking the vehicle. In the common ONSTAR system, cellular telephone technology is used to activate the GPS receiver and to transmit the location data to the ONSTAR service center. ONSTAR is a registered trademark of OnStar Corporation of Troy, Mich.
Goods shipped to a destination from a manufacturing plant, warehouse or port of entry are normally tracked to assure their timely and safe delivery. Tracking has heretofore been accomplished in part by use of various shipping documents and negotiable instruments, some of which travel with the goods and others of which are transmitted by post or courier to a receiving destination. This paper tracking provides a record which is completed only on the safe delivery and acceptance of the goods. However, there sometimes is a need to know the location of the goods prior to delivery or acceptance. Knowledge of the location of goods can be used for inventory control, scheduling and monitoring.
Shippers and/or distributors have provided information on the location of goods by tracking their vehicles and knowing what goods are loaded on those vehicles. Goods are often loaded aboard shipping containers or container trucks, for example, which are in turn loaded aboard railcars. Various devices have been used to track such vehicles. In the case of railcars, passive radio frequency transponders mounted on the cars have been used to facilitate interrogation of each car as it passes a way station and supply the car's identification. This information is then transmitted by a radiated signal or land line to a central station which tracks the locations of cars. This technique, however, is deficient in that whenever a particular railcar remains on a siding for an extended period of time, it does not pass a way station. Moreover, way station installations are expensive, requiting a compromise that results in way stations being installed at varying distances, depending on the track layout. Thus, the precision of location information varies from place to place on the railroad.
Recently, mobile tracking units have been used for tracking various types of vehicles, such as trains. Communication has been provided through the use of cellular mobile telephone or RF radio link. Such mobile tracking units are generally installed aboard the locomotive which provides a ready source of power. However, in the case of shipping containers, container truck trailers and railcars, a similar source of power is not readily available. Mobile tracking units which might be attached to containers and vehicles must be power efficient in order to provide reliable and economical operation. Typically, a mobile tracking unit includes a navigation set, such as a GPS receiver or other suitable navigation set, responsive to navigation signals transmitted by a set of navigation stations which may be either space-based or earth-based. In each case, the navigation set is capable of providing data indicative of the vehicle location based on the navigation signals. In addition, the tracking unit may include a suitable electromagnetic emitter for transmitting to a remote location the vehicle's location data and other data acquired from sensing elements on board the vehicle. Current methods of asset localization require that each item tracked be individually equipped with hardware which determines and reports location to a central station. In this way, a tracked asset is completely “ignorant” of other assets being shipped or their possible relation to itself. In reporting to the central station, such system requires a bandwidth which scales approximately with the number of assets being reported. The aggregate power consumption over an entire such system also scales with the number of assets tracked. Further, because both the navigation set and the emitter are devices which, when energized, generally require a large portion of the overall electrical power consumed by the mobile tracking unit, it is desirable to control the respective rates at which such devices are respectively activated and limit their respective duty cycles so as to minimize the overall power consumption of the mobile tracking unit.
Most present-day asset tracking systems are land-based systems wherein a radio unit on the asset transmits information to wayside stations of a fixed network, such as the public land mobile radio network or a cellular network. These networks do not have ubiquitous coverage, and the asset tracking units are expensive. A satellite-based truck tracking system developed by Qualcomm Inc., known as OMNITRACS, is in operation in the United States and Canada. This system requires a specialized directional antenna and considerable power for operation, while vehicle location, derived from two satellites, is obtained to an accuracy of about one-fourth kilometer. U.S. Pat. No. 5,129,605 to Burns et al., incorporated by reference herein, describes a rail vehicle positioning system for installation on the locomotive of a train and which uses, to provide input signals for generating a location report, a GPS receiver, a wheel tachometer, transponders, and manual inputs from the locomotive engineer.
In an asset tracking system disclosed in U.S. Pat. No. 5,651,800, entitled “Local Communication Network for Power Reduction and Enhanced Reliability in a Multiple Node Tracking System” by Welles et al. and in U.S. Pat. No. 5,588,005 entitled “Protocol and Mechanism for Primary and Mutter Mode Communication for Asset Tracking” by Ali et al., both of which are incorporated herein by reference, a tracking system based on a “mutter” mode local area network is used to generate data that is transmitted to a central station. In this asset tracking system, there are two modes of communication. One mode is communication between the central station and the tracking units, which is usually via satellite. The second mode is a local area network, referred to as the “mutter” mode, between tracking units. One of the tracking units, denoted the master unit, communicates with the central station.
One of the chief challenges in using the first mode of communication is to devise a protocol for the communications that will provide efficient use of the communication facilities and respect the special sensitivities of the reporting scenario. Such protocol should meet the following guidelines:
1. The protocol should be two-way, thereby supporting transmission to and from a central station.
2. The protocol must accommodate a large number of assets and be scalable so that assets can be added and deleted without impacting normal service.
3. The protocol must accommodate variable length messages. The variable length may arise from a number of considerations; for example, the individual asset may have extra sensor data to report in addition to its location.
4. The protocol must have a chatter suppression feature to allow selective turn-off of a specific malfunctioning asset's transmitter.
5. The protocol must function efficiently if used over an extremely long path such as is implied by use of a geostationary satellite.
6. The protocol must allow encryption or a privacy feature to be added later without significantly impacting the capacity.
7. The protocol must be sufficiently robust to allow an asset to enter the system at any time without knowledge that cannot be gleaned following its entry into the system, and must tolerate occasional transmission errors and not be unstable but degrade gracefully under additional load.
8. The protocol must not require the assets to be receiving all the time but accommodate a duty cycle significantly less than 100% for periods of monitoring communication frequencies.
The protocol must be designed to be easily adjusted and nominally reprogrammable to allow presentation of its efficiency as the operational scenario matures.
The term “telematics” is often used to refer to automobile based asset tracking systems that combine GPS satellite tracking and wireless communications for automatic roadside assistance and remote diagnostics.
Referring to FIG. 1, there is shown a block diagram illustrating a general telematics system 100 in accordance with the prior art. Typically, a telematics system 100 includes services 110, platforms 120, networks 130, auto/freight sector clients 140, and positioning technologies 150. The services 110 provided by the telematics system 100 may include automatic roadside assistance, accident notification, traffic information, diagnostics, mobile Internet access, fleet management, and navigation. The platforms 120 on which the telematics system 100 may update may include servers, gateways, and billing and customer-care call centers. The networks 130 by which communications are provided may include voice, short messaging system (“SMS”) messaging, and wireless application protocol (“WAP”). The auto/freight sector clients 140 serviced by the telematics system 100 may include passenger vehicles, trucks, freight, public safety applications. Typically, telematics systems 100 perform applications including vehicle or equipment (i.e., asset) location, driver concierge services, fleet management, and navigation/traffic information services.
Typically, an asset tracking device or module is installed in the vehicle to be tracked. The location of the device is determined by the telematics system 100 using a positioning technology 150, such as GPS or time difference of arrival (“TDOA”). The location information is then provided to an application to service a customer.
Briefly, the GPS was developed by the U.S. Department of Defense and gradually placed into service throughout the 1980s. The GPS satellites constantly transmit radio signals in L-Band frequency using spread spectrum techniques. The transmitted radio signals carry pseudorandom sequences which allow users to determine location on the surface of the earth (within approximately 100 feet), velocity (within about 0.1 MPH), and precise time information. GPS is a particularly attractive navigation system to employ, being that the respective orbits of the GPS satellites are chosen so as to provide world-wide coverage and being that such highly-accurate radio signals are provided free of charge to users by the U.S. government. The main problem with current GPS technology is the requirement for an unobstructed view of the sky for communication with GPS satellites. Its advantage is that is can provide a location anywhere in the world without any additional infrastructure on the ground. Improved receiver performance and signal processing and new technologies, like “Enhanced GPS,” will provide locations where traditional GPS would fail.
On the other hand, TDOA uses the existing cellular network infrastructure to determine location. Referring to FIG. 2, there is shown a flow diagram illustrating a typical TDOA process 200. The process requires signal timing information from at least three different antenna sites. At step 1, a handset or vehicle places a call (e.g. a 911 call). At step 2, antennae receive the signal from the handset or vehicle and pass it to a carrier's mobile switching office. At step 3, TDOA equipment measures the difference in the time the cellular radio signals arrive at the antenna sites and translate that data into location data (i.e., longitude and latitude data). At step 4, the carrier forwards voice call and location data to a Public Safety Answering Point (“PSAP”). The use of TDOA is typically restricted to areas where coverage from multiple towers is available.
The communications networks 130 for linking tracking devices to platforms 120 to provide services 110 to customers include cellular and telephone networks. With respect to cellular networks, network providers typically make use of the Advanced Mobile Phone System (“AMPS”) control channel frequencies for the transfer of small data packets. The use of the cellular network control channel provides more robust communication than cellular voice traffic so that it is possible to communicate with devices located in places where ordinary cell phones have marginal or intermittent voice coverage. Clients of these virtual carriers can make use of a TCP/IP data link to connect their operations centre to the virtual carrier network which then provides continent wide coverage through cellular service providers.
For example, in U.S. Pat. No. 6,131,067, to Girerd, et al, a client-server based system is described in which the location of a tracking device is determined using GPS information. This location is then reported to a user via the Internet. The entire disclosure of U.S. Pat. No. 6,131,067 is hereby incorporated by reference.
It would be of significant benefit if existing telematics systems could be adapted for tracking medical devices and/or sterilization cases. Medical devices may include medical implants, medical instruments, and other components.
There is a need in the art for a system and method for locating missing sterilization cases and/or medical devices. Further, there is a need in the art for a system that provides instruction to medical personnel on how to perform certain procedures or how to use certain medical instruments. Finally, there is a need for continued improvement in the area of hospital inventory management.